1. Field of the Invention
Embodiments of the present invention relate to a method and apparatus for cleaning a pad used in chemical mechanical polishing (CMP) or electrochemical mechanical polishing (ECMP).
2. Description of the Related Art
ECMP is one method of planarizing a surface of a substrate. ECMP removes conductive materials from a substrate surface by electrochemical dissolution while polishing the substrate with a reduced mechanical abrasion compared to conventional CMP processes, which may require a high relative down force on a substrate to remove materials, such as metals and metal containing layers, from the substrate.
The polishing pad is one of the most critical parts for CMP or ECMP. The success or failure of the polishing process largely depends upon the pad. The pad has taken on a greater importance in recent years in ECMP wherein the pad provides two equally important functions, providing electrical contact to the substrate and providing surface abrasion. The pad to substrate contact area is what determines the pad performance in a polishing process, so it is critical to have a pad cleaning process that provides the best possible pad surface properties.
The surface of the pad is periodically conditioned to restore polishing performance. Conditioning is typically an abrasive process that may leave particles or other contaminants on the pad surface. To remove these contaminants, the pad is cleaned during and/or after conditioning.
One method for cleaning a pad includes rinsing the pad with a high pressure jet of liquid. Although high pressure rinsing may be suitable for cleaning conventional dielectric pads, the cleaning efficiency of a simple high pressure rinse is insufficient for ECMP processes due to the nature of the conductive pads utilized for ECMP processes. For example, debris located deep inside perforations in the conductive pad may be moved to the pad's surface during high pressure rinsing. Once at the pad's surface, the contaminants may stay on the surface or within scratches that are present on the surface of the pad.
There is a need in the art to provide an effective method and apparatus for cleaning polishing pads.